The down votes were because you clearly didn't understand what preemption(or that this is really about it being a realtime flag) is or add much to the conversation(mentioning anything at all that might add something, like even a bad question, "I heard people using raspberry pis for embedded, would this help?"). The downvotes on the other guy are because asking for feedback on downvotes is discouraged.

To contribute, the PREEMPT_RT has been around as a set of patches(if not this specific one, then at least some version of making linux a realtime os.). If you need to know that something will run within a specified amount of time realtime matters.

EDIT: Don't use this and think it will help performance, generally it kills throughput.